Screen for stereo viewer



" HQSRM'AN, an., 3,208,341"

sepas-,1965i l I n ASCREEN rn STEREO' umm' l v 61 Sheds-Sheet 4,

- Ameel :und fr. 1952 Quai NON

lCONNOR y vIN1/mms; HARRY 1.. HosTERMAN JR. a'Asn. M. MADIGAN ROUERIC H.

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l IN1/mfom' HARRY 1 HosTERMAN JR. aAsu. M.- MADIGAN BY RooERlc. H.

'CON NOR Av onusv United States; Patent Olnce 3,208,341 SCREEN FoR STEREO viEwER Harry L. Hosterman, Jr., Akron, Basil M. Madigan,

Wadsworth, and Roderc H. OConnor, Akron, Ohio,

' ss'signors to Goodyear Aerospace Corporation, a corpoy ration of Delaware v [Filed June'v, i962, ser. No. 200,129 i ciatm. (ci. en -zsm)` This invention relates to a stereo viewing system and, more particularly, to a back viewing stereov apparatus which includes a light selective composite screen and an adjustable light projection system.

I'Ieretofore' it has been known to project left and right stereographic views either simultaneously or alternately in substantially superimposed relation upon a composite image screen. One of the prior art composite-screens contains alternate parts of opacity and transparency which separates the projected left-and right stereographic views into a plurality of left andrightimage bands.- Ihis screen directs light vfrom the independent le'ft and right image portions so that the left and right eyes of an observer may seethe left and right image bands respectively and exclusively. Some amount of three-dimensional perception is thus achieved.

Selective screens have been developed to resolve pro jected left and-right stereographic views into left and right image bands. -These screens contain optical structures having a lenticular shape'. The rays of light that pas's through the lenticular ridges form substantially independent vertical alternately disposed left and right' image bands upon the screen. The' effect is three-dimensional perception.

'I'he contrastand resolution of the image obtained with these priorva'rt stereo viewers are of `low quality. The images are blurred'an'd noncontinuous. 1"The viewers' have limited. image control characteristic and the view 'i control characteristics are notfcoordinated with the optical characteristics of the screen.

'Ihe screens have the disadvantage' of being expensive and diicult to fabricate accurately. A l Y It is Jthe general object of the invention to avoid and overcome the foregoing and other.- ditiiculties 'of andobjections toprior art practices by the provision of a relativelyinexpensive, simplified and adjustable stereo viewer possessing apparent continuous three-dimensional images of high quality.

A further object o the invention'is' to provide a singlei screen stereo imagery to an observerwithout the need for special glasses or filters in any of ,the viewing paths of the iight; 1 y

Another object'of the invention isl to provide a stereo viewer with a linkage which functions to automatically focus the projectedl image.

Another'object of the invention lis to provide a stereo viewer which is capable of viewing varying amounts of image overlap. v j

' Another object ofl the invention is to provide a stereo viewing's'ystem'which has a screenwhich reproduces the projected scene' with a large amount of resolution and contrast. 4 A

Another,l object of theinvention is to provide a stereo viewer which permits the interpreter to move the images in X, Y, arid Z directions and lto rotate the image to 'equalize the Y parallex.

According to the invention, a light projecting optical system,vhaving .controls to alter the direction of the light rays in the X direction, the Y direction and to rotate the v light rays tof `equalize the Y parallex, projects superimposed images upon a transparent light selective, composite screen. The optical system includes an automatic focusrelationship. One member is a Fresnel lens. The othermember is a sheet of transparent lm material having minute three-dimensional optical elements. Each elcment is a lens and functions to transmit light energy iii-a predictable direction. The composite screen 'directs the left and right stereographic image portions exclusively to the left and right eyes of th observer.

The exact nature of the invention as well as other objects and advantages thereof will be readily apparent from the consideration of the following specification relating to the annexed drawing in which:

FIGURE 1 is a diagrammatic view of a stereo viewing system according to the invention.

FIGURE 2 is a cross-sectional view of a portionof'the y viewing screen laminate.

. of the stereo viewing apparatus "taken along the line 6-1 of FIGURE 4. y

` FIGURE 7is.' a sectional view of themirror adjusting mechanism taken along the line 7-7 of FIGURE 6.-

FIGURE 8 is a plan view of theoptical systemu'ant` optical adjusting mechanism of the stereo viewing appa ratus taken along' the axisof the lens,` line 8-8 .of FIG URE 4. I

FIGURE 9 is a diagrammatic view of the basic linkagi mechanism for automatic .foeusingan optical system.

FIGURE l0 is a diagrammatic viewof the linkagl mechanism for automatically focusin the lens system oi the stereo viewing apparatus of FIG RE 8. i

FIGURE 1l is a perspective view of the drive washe in the linkage mechanism of FIGURE 10.

Referring to the drawings, there is shown in FIG. a basic diagrammatic view of the stereo viewing systei generally'ndicated by number 10. The system include avpair of projectors l2 and 14. Projector 12 has a ligl source 16,. a condensing lens system 18, and a lens 2f A positive transparency 22 is positionable in the prt jector between the condensing lens system 18 and tb lens 2t). The projector 14 includes a light source 24, condensing lens system 26, and a lens 28. A positii transparency 30 is positionable in the projector betwee the condensing lens system 26 and the lens 28. The pos tive transparencies 22 and 30 are stereo pairs.

The light projectors 12 and 14 are angularly positioni with respect to each other to project left and right sten views in' or near superimposed relationship upon an ima,` screen 32. The composite screen 32A is positioned norm to the bisector of the angle formed by the lightprojecto throw axes. The screen functions to direct the left a1 right stereographic image projected thereon exclusive to the left and4 right eyes respectively of ari observer 3 The screen forms precisely defined audience spaces optical image formation. The audience space is deti mined by the viewing angle established by the screen.

As shown in FIGS. 2 and 3 the composite screen 32 formed from a Fresnel lens 36 and a semi-specular n terial 38. The Fresnel lens-and semi-specular mater are in face to face relationship and are supported a protected iby rigid transparent members 40 and 42. 'I Fresnel lens and semi-specular material are sandwicl between the rigid and transparent members. The Frcs lens functions as a field lens to direct the light to I 3,208,341 i Patented Sept; 28, 1965 3 viewer from all parts o'f the screen. -The Fresnel lens is a combination of small lens segments reduced to a flat plane. h

The semi-specular screen material 38 as shown ln FlG.

3 has a transparent lm base 44 that has been treated to provide a three-dimensional pattern surface on one side. The patterned surface consists of minute geometric optical elements 46. There are approximately one million elements per square inch of material. Each element` is a lens and functions to direct its transmitted light rays in a predi'ctable direction. .The pattern consists of adjacent minute lens elements, ea'ch element ranging between one and t'wo thousandths of an inch in extent. The geometry of the elements control the size of the audience space by controlling the viewing angle. The elements may be shaped as pyramids, cones, cylinders, or four-sided pyramidal prisms. The enlarged cross section of the semispecular material shown in FIG. 3 shows the surface of the material as havin-g pyramidal geometric elements 46 of varying height separated by semi-spherical cavities 48. The geometric shape and size of the optical elements and the orientation of the individual elements are variables which control the directional characteristics of the screen to define specific audience spaces. The pattern shown in FIG. 3 is a random arrangement of varying height pyramidal geometric optical elements. This pattern of pyramidal geometric optic elements results in a viewing angle in the X dire'ction o f about ten degrees and an angle in the YV direction of a-bout forty degrees.' The resolution or breaking up and contrast characteristics of the semispecular screen material is a function of the screen's surface :granularity or pattern size.

Referring to iFIG. 4, a back view-ing stereo apparatus 50 is positioned in a rectangular container 52. The apparatus incorporates the principles ofthe stereo viewing system disclosed in FIG. l. The screen 32a, pivotally secured to the front po'rtionof the container 52, is substantially identical to the screen 32 of FIG. 1. The sterco apparatus is built on a skeleton frame 54 which is removably fastened in the container'52.

Referring to FIG. 5, the light source 56 of the apparatus is mounted infront of a pair of angularly disposed mirrors 58 and 60. The lightl rays emitting from the light source 56 are reflected by the mirrors 58 and 60 into two distinct paths through the condensing lens 62 and 64 into a pair'of mirrors 66 and 68. The mirrors 66 and 68 are manually adjustable about their X and Y ax'es. Bolts 70 and 72 pivot the respective tmirrors about the Y axis on brackets 74 and 76.. These brackets are secured to rota'table shafts 78 and 80. The shafts 78 and 80 are frictionally held in a portion of the frame 54 to rotate the mirrors about their X axis. A pair of condensing lenses 82 and 84 are positioned in the reflected light paths of the adjustable mirrors 66 and 68.

As shown in FIG. 6 a film supporting plate 86 having a pair of horizontally spaced apertures 88 and 90 is mounted on the frame 54. The aperture 88 is positioned below the condensing lens 82 and the aperture 90 is positioned lbelow the condensing lens 84. A stereo film 92 having positive stereo images is positioned on the support` ing plate 86 and extends over the apertures 88 and 90.

4A pai'r of angularly disposed left mirrors 94 and 96 are positioned below the aperture v88. A pair of angularly disposed right mirrors 98 andv100 are positioned below the aperture 90. The mirrors function to reect the light rays projected through the transparent film into the optical systems of the viewer. Mirror 96 is secured to a vertically disposed plate 102 at an angle of 45 degrees with respect to the horizontal. The mirror 94 secured to the plate 102 at an angle of 38 degrees with respect to the horizontal. A pivot pin 104 extending through the plate 1'02 at a point established by the intersection of the planes of the mirrors rocka-bly mounts the plate 102 on a guide plate 106. A left spring 108 extending over the pivot pin 104 enga-ges the support plate 102 and a stop pin 110 to 4. bias the plate 102 about the pivot pin 104. A cam rod 112 secured to the plate 102 in a plane substantially parallel to the plan'e of the mirror 94 engages a portion of the frame 54. The spring 108,funclions to hold the cam rod 11'2 in engagement with the frame 54. 106 has a three-point suspension engagement with the frame 54. A pair of vertically spaced and horizontally extending ears 114 and 116 engage slots 115 and 117 in frame 54. A single ear 118 extending in an opposite horizontal direction from the ears 114 and 116 is posi-A tioned in a slot 119 in a frame 54. The slots permit the guide plate to move in a horizontal direction and pivot about a vertical axis intersecting the ears 114 and 116. An eccentric cam 120 manually rotatable by shaft 122 engages the edge of the guide plate 106. Rotation of the cam urges the guide plate in a horizontal direction against the force of the tension spring 123. Movement of the guide plate 106 in a horizontal direction rotates the mirrors 94 and 96 by the interaction of cam rod 112 on the frame 54. This rotation prevents the mirror 94 from 'engaging the mirror 98. The manually rotatable shaft is supported at one end -by the control panel 124 and at the other end by a portion of the frame 54.

The angularly disposed right mirrors 98 and 100 are secured to vertical plate 126. The mirror 98 is disposed at an angle of 38 degrees with respect to the horizontal and the mirror 100 is disposed at an angle of 45 degrees with respect to the horizontal. The plate 126 is pivotally mounted by pivot pin l128 to the vertical guide plate 130- The pivot pin 1 28 extends through the support plate '126 at a point defined by the intersection of the planes of the mirrors. A leaf spring 132 engages the support platea-126. extends over the pivot pin 12,8 and engages a stop p n 1 34 to rotatably bias the support plate. A cam rod 136 secured to the support plate 126 in a plane substantially parallel to the plane of the mirror 98 engages a portion o f the frame 54. T-he leaf spring V132 biases the cam rod 136 against the frame 54.

The guide plate has va three-point suspension on the frame 54. This suspension isk provided by a pair of horizontally extending and vertically spaced ears 138 and i 140 positioned in slots 142 and 144 in the frame 54 andv a single horizontally'. extending ear 1426. The ear 146 is positioned in the slot 119 in the same plane as the ear ment of the guide plate 130 by the eccentric cam 148 in-----n a horizontal direction rotates the mirrors 98 and 100 as a unit 'about the pivot pin 128. This rotation controlled by the engagement of the cam rod 136 with the housing 54 pgrevents the mirror 98 frominterfering with the mir.- ror 4. I

The pair of right mirrors and the pair of left mirrors simultaneously rotate on vertical axes in an opposite sense. As shown in =FIG. 7, a hollow set screw 154 having a transverse pin 156 extends through the housing 54 in a threaded bore 157 and engages the ears 118 and 146 of the guide plates 106 and 13o. A manually rotatable slotted shaft 158 mounted on the rcontrol panel 124 is .used as a tool to rotate the screw 154. A compression spring 160 engages the ears 118 and 146 and a frame 54-to urge the ears in engagement with the end of the screw 158. The ears 118 and 146 follow the movement of the screw 158.

A left mirror 162 and a right mirror 164 is pivotall'y mounted to the frame 54 above the mirrors 96 and 100 respectively. The mirror 162 shown in .F IG. 4 is pivotally mounted on the frame 54 by a hinge 166. The mirror is pivoted on a horizontal axis transverse to the axisof the optical system. A leaf spring 168 in engagement with .a portion of the mirror urges the mirror `against an adjustable screw 170 mounted in the control Apanel 124. The

angular position of the mirror 162 is controlled by the The guide plate vertical axes is accomplished by themovement ofthe screw means 154 shown in FIG. 7. This rotation rotates the images on' the screen. Therotationof the images on the screenl results in thel equalization ofthe Y parallex.

.While there. have been shown, descrbed, and pointed .out-.the 4furidamentaljnovel features'tof .the invention as applied to the preferred embodiment, it willbe understood ,--What is claimed is: 'v

` In an optical screen adapted torelceive projected superimposedimages so. that the images will' "be viewable in 'stereoscopic relief, the combination of transparent plastic sheetv having'one side treated to l provide a three-dimensional pattern surface which consists of geometric optical elements ranging lbef Ween a'bout one and about two thous-andthsv of an inch in extent, vsaid elements being of pyramidal geo `y l metricshape and of varying height and arranged at random, said elements adapted to; transmit incident light rays in a predictable direction,

#a pair of rigid transparent members operatively ,iiecured Qq; Ato the outsides ofthe Fresnel lens andthe transparent sheet for support and protection thereof. Y

References Cited by the Exrmiinerv y UNITED STATES PATENTSA 2,150,225 3/39 Kaszab I .'ss-4283s 2,260,228- 10/41 Moller etal. j 1 '2,529,701 11/50 Maloff 88'2 8 .93 2,589,014 3 /52 McLeod 3525-139. A2,700,322 i/ss Gruber -,ssf-N I2,726,573 12/55 Ma1off--...-` 88-12833 2,823,580 2/5-8 Gannett 88-24 I l2,891,444 6/59 Ewald 88`|29 2,987,961 6/61 Cotton et al. '88'84 v 13,037,423l 6/62 a hat Fresnel lens positioned in face -to face relation l with the treated surface of said transparent sheet'V 'v and adapted to'direct the light passedthrongh said transparent sheet, and y -JULIA E. COINER,v Primmyfaxaminer. 

